InstrumentTrack: do not try to load "libconnection.so" in compat code

In compat code of InstrumentTrack::loadTrackSpecificSettings() also
check for nodeName being equal to ControllerConnection::classNodeName().
This avoids trying to load the non-existing instrument "connection".
In master branch this has been fixed ugly in commit 22c877d4 before,
however implement a cleaner solution which is also suitable for
backporting.

Closes #3021259.
(cherry picked from commit 65311ef2b4)

src/core/ControllerConnection.cpp

@@ -3,6 +3,7 @@
  *            which handles the link between AutomatableModels and controllers
  *
  * Copyright (c) 2008 Paul Giblock <drfaygo/at/gmail.com>
+ * Copyright (c) 2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
@@ -208,12 +209,6 @@ void ControllerConnection::deleteConnection()
 	delete this;
 }
 
-QString ControllerConnection::nodeName() const
-{
-	return( "connection" );
-}
-
 
 #include "moc_ControllerConnection.cxx"
 
-